MEDICINE AND PHYSIOLOGY
IN UNUSUAL ENVIRONMENT
• Mountain Medicine
• Under-Water Medicine
• Medicine on Exposure to
Extremes of Temperature
• Space and Aviation Medicine
• DEEP-SEA DIVING
PHYSIOLOGY
• SUB AQUATIC MEDICINE
• UNDER-WATER MEDICINE
CASE
A sailer dived in the sea upto about
100 feet depth. When he came back
to the surface of sea, he was
exhausted, complained of severe
pain and swelling of joints [esp knee
and ankle joints] and hardly could
move those. Some skin rashes were
visible with severe itch. He was a bit
drowsy and disoriented.
OBJECTIVE
“To have safe diving“
To Learn:• Orientation Under-Water
• Pathophysiology of Under-Water
Medicine
• Medical Problems [Disorders] of DeepSea Diving
• Decompression Sickness
• Uses of Hyperbaric Oxygen Therapy
USES OF DEEP SEA DIVING
• RECREATIONAL
• OIL & SALVAGE
• COMBAT
ORIENTATION UNDER WATER
• VISION
• HEARING
• EQUILIBRIUM
• RULES FOR DIVING
EFFECT OF SEA DEPTH ON PRESSURE
AND ON GAS VOLUMES
Depth (feet)
Sea level
Atmosphere (s)
1
33
2
66
3
100
4
133
5
166
6
200
7
300
10
400
13
500
16
FACTORS AFFECTING IN DIVING
•
•
•
•
•
•
•
Total Pressure [Depth]
Duration of Dive
Activity of Diver
Temp of Water
Drugs within body
Gas Mixtures
Rate of Descent/ Ascent
EFFECTS OF DIVING
HEMATOLOGICAL
• Hct
• Platelets
• DLC
• TLC
• Diuresis
• Weight Loss
• Rise in NH4
RESPIRATION
• CO2 Retention
• Dyspnoea
•
Ventilation
CVS
• Arrhythmias
• Hypertrophy
•
Cardiac Contractility
• R.V. Overload
RENAL
• Diuresis
• Resp Acidosis
NEURAL
• Disturbed mental and
motor functions
• Loss of Long-term
memory
HORMONAL
•
Nor-epinephrine
•
Epinephrine
•
Dopamine
PATHOPHYSIOLOGY OF UNDER-WATER
MEDICINE
•
BAROMETRIC PRESSURE
•
VOLUME OF GASES
•
INTRA-THORACIC PRESSURE
•
INTRA-ALVEOLAR PRESSURE
PATHOPHYSIOLOGY
PARAMETER
DEEP SEA HIGH
DIVING
ALTITUDE
• Barometric Pressure
• Volume of Gases
• Intra-thoracic Pressure
• Intra-alveolar Pressure
[Compression]
[Expansion]
MEDICAL PROBLEMS OF
DEEP-SEA DIVING
Problems on Descent
• Oxygen Toxicity
– Lung damage
– Convulsions
• HPNS
– Tremors
– Somnolence
• CO2 Toxicity
– Initial excitation and later depression of
respiration
– Respiratory acidosis
– Lethargy
– Narcosis
MEDICAL PROBLEMS OF
DEEP-SEA DIVING
Problems on Descent
• Nitrogen Narcosis
– Euphoria
– Impaired performance
– Anesthetic effects
• Ear & Sinus
Barotraumas
MEDICAL PROBLEMS OF
DEEP-SEA DIVING
Problems on Ascent
• Decompression Sickness
• Air Embolism
DECOMPRESSION SICKNESS
OR
BENDS
OR
HYPER-BARISM
OR
DIVER’S PARALYSIS
HISTORY
1670 : Boyles described “Decompression”
1830 : Cochrane used compressed air in
tunnels and Caissons
1937 : Behnk – discovered “N2 Narcosis”
DECOMPRESSION SICKNESS
• Pathophysiology
• Resp Gases at 1 ATA
• Gaseous Pressures Outside / Inside
Alveoli of Lungs
• Decompression Sickness Sequence
• Decompression Sickness Grading
• Few Pictorial signs of DCS
• Factors Influencing DCS
• Treatment of DCS
• Uses of Hyperbaric Therapy
• Prevention of DCS
PARTIAL PRESSURES OF RESPIRATORY
GASES AT 1 ATA
Sample
Gas Partial Pressure
O2
[mm Hg]
CO2
N2
[mm Hg] [mm Hg]
H2O
[mm Hg]
Total
[mm Hg]
Inspired air
158
0.3
596
5.7
760
Expired air
116
32
565
47
760
Alveolar air
100
40
573
47
760
Arterial
blood
100
40
573
47
760
Venous
blood
40
46
573
47
706
Tissues
< 30
> 50
573
47
700
STP = 760 mmHg
Maximum Human Tolerance
= 4 – 6 ATA for 4 hours
PRESSURE OUTSIDE BODY
Gaseous pressure both inside and outside the body, showing at left
saturation of the body to high gas pressures when breathing air at a total
pressure of 5000 mm Hg, and at right the great excess of intrabody
pressure that is responsible for bubble formation in the tissues when the
body is returned to the normal pressure of 760 mm Hg.
DECOMPRESSION SICKNESS SEQUENCE
DECOMPRESSION SICKNESS GRADING
Type I [Pain only]
Type II [Serious]
• Limb or joint paindysfunction
• Itch
• Skin rash
• Localized swelling
• Central nervous
system disorder
• Inner ear damage
• Lungs failure
• Cardiac failure
FACTORS INFLUENCING DCS
• Exertion
• Physical fitness
• Temperature – cold
water, hot shower
• Sex – females
• Age
• Obesity
• Dehydration
• Increased carbon
dioxide pressures
•
•
•
•
•
Alcohol intake
Physical injury
Adaptation
Dive profile
Rapid and multiple
ascents
• Repetitive and
multi-day diving
• Altitude exposure
Skin lesions of
decompression
sickness. This
diver, who had had
an upper limb
amputation,
developed ‘bends’
pain in the
phantom limb, and
skin bends over
the body. Both
responded rapidly
to recompression
therapy.
(Photograph by
courtesy of Dr
Ramsey Pearson)
Decompression sickness: skin lesions of isobaric counterdiffusion.
The subject breathed a neon/oxygen mixture at 1200 feet (360
metres), while exposed to a chamber of helium/oxygen. Gross
itching accompanied the intradermal bubbles. (Photograph by
courtesy of Professor C. J. Lambertsen)
Curved and concentric lacerations of shark bite – often
with teeth left in the wound. (Photograph courtesy of
Dr. G. D. Campbell)
TREATMENT OF
DECOMPRESSION SICKNESS
INVOLVES IMMEDIATE
RECOMPRESSION, FOLLOWED
BY GRADUAL
DECOMPRESSION
LOCALIZED PAIN IN OR
AROUND A JOINT MAY
SOMETIMES BE RELIEVED BY
APPLICATION OF LOCAL
PRESSURE, e.g FROM
AN INFLATED
SPHYGMOMANOMETER CUFF
• The value of 100% oxygen, before
during and after recompression
– Intravascular bubbles do not develop
with oxygen breathing, [especially at 2
ATA]
– Denitrogenation is maximized, reducing
tissue bubbles
– It reverses the development and the
redevelopment of DCS
PREVENTION
• GRADED ASCENT
• USE OF SCUBA
• USE OF HELIUM
TREATMENT
• HYPERBARIC OXYGEN THERAPY
[RECOMPRESSION THERAPY]
• SUPPORTIVE THERAPY
USES OF HYPERBARIC
[RECOMPRESSION] THERAPY
•
•
•
•
•
•
•
Gas Gangrene
Decompression Sickness
Arterial Gas Embolism
Severe Burns
Myocardial Infarction
Osteomyelitis
Carbon Monoxide Poisoning
